When it comes to future-proofing your farm for efficient production, weighing your cows can make a huge difference.
While weighing calves and heifers is a common industry practice, weighing cows regularly is still a foreign concept for most New Zealand farmers. Implementing a weighing process however can have a dramatic impact on production and farm profits.
The general rule of thumb is heifers should weigh 30% of their mature weight by six months of age, 60% at 15 months (mating), and 90% at 22 months (pre-calving).
To ascertain the mature weight, farmers generally use industry calculations such as liveweight breeding value (Lwt BV) using data from the herd recording provider; weighing a selection of mature cows to gauge an average across the herd; or using a breed-based average mature weight: Jersey (around 410kg), Crossbred (482kg), or Friesian (524kg)1.
Once a heifer is fully grown and in-calf, they are rarely weighed again with farmers focusing on body condition scoring to gauge health and production.
Fonterra Technical Advisor – Animals Tim Johnstone, says to accurately forecast your herd’s breeding worth (BW) and production worth (PW), you need to know individual numbers across the full herd.
“Knowing your cow’s real weight is key to spotting your most efficient animals. That’s the key to helping you make smarter, more crucial decisions around what animals you’re breeding and what you’re culling. Rather than just guessing, get the actual numbers,” he says.
“You can have two cows the producing the same amount, and one is say, 50 or 100 kilos heavier than the other. The most efficient cow is obviously the smaller cow as it has less maintenance requirements for that body mass but you’re getting the same in production. Farmers need to be able to identify their most efficient cows based on what they’re producing versus their body weight.”
According to LIC, being weighed even once in a lifetime can make a significant difference to the breeding values and production values of individual animals.
The optimal time for most farms to weigh your cows is between December and February, as they are well past calving and not yet in the later stages of pregnancy. However contemporary grouping takes care of things in most cases – in fact, weights collected up to 305 days post calving are useful for animal evaluation.
DairyNZ recommends heifers should ideally be weighed every 4-8 weeks (12-weekly at a minimum). Research has found that every 1% below target weight equates to a production loss of 2kg milk solids in their first lactation2. Regular weighing allows farmers to jump on any problems if a heifer is falling behind goal weight and get them back on track.
“Weighing heifers during the growth phase is crucial but it is equally important to know your cows’ weight at fully grown so that you can accurately track efficiency of production. As an industry, we are moving towards a system of quality over quantity. In this sense, it is essential to have the best cows on-farm,” says Tim.
There are several companies nationwide, including LIC, that offer on-farm weighing services. Farmers also have the option to invest in weighing equipment. Ideally weighing systems need to be easy to use and allow data to be integrated into herd management systems. Farm Source has a range of different weigh scale systems available for purchase in-store.
For more information regarding the benefits of weighing your youngstock, heifers and herd talk to your Farm Source TSR.
1 DairyNZ Liveweight targets https://www.dairynz. co.nz/animal/heifers/lw-targets.
2 McNaughton, L., Lopdell, T. Effect of heifer live weight on calving pattern and milk production. Proceedings of the New Zealand Society of Animal Production: 2013, Vol 73: 103-107